Polyester film supports are well known. Their use as supports in photographic elements is an example. For use in the latter elements, the polyester film support must be coated with layers, referred to sometimes as a subbing layer, to promote adhesion between the polyester film support and other emulsion layers in the photographic element, such as gelatin silver halide layers.
A commercial process used for promoting adhesion polyester film supports involves extrusion and biaxial orientation of, for example, a poly(ethyleneterephthlate) film support according to well known techniques disclosed, for example, in U.S. Pat. Nos. 2,779,684 and 2,627,088. The resulting polyester film support is then discharge-treated. This discharge treatment can be by, for example, plasma or corona discharge. A coating composition is then applied to the support to provide adhesion between the support and subsequently coated layers. Emulsion layers, such as gelatin silver halide layers are then coated over the adhesion-promoting layer.
Frequently used polymer materials, such as poly(methyl acrylate-co-vinylidene chloride-co-itaconic acid) and poly(acrylonitrile-co-vinylidene chloride-co-acrylic acid) disclosed in U.S. Pat. Nos. 3,201,249 and 3,143,421 respectively, do not provide coating compositions which are sufficiently adhesive to polyester film supports when used in the above-described commercial process. Coatings which provide better adhesion are desired.